Implantable systems for cardiac rhythm management often employ medical electrical leads extending into the venous blood stream and being coupled to a surface of the heart. Typically, a medical electrical lead includes one or more electrodes for stimulating the heart and sensing electrical activity of the heart. In order to provide better management of cardiac conditions, the lead may also include a physiological sensor. The inclusion, on a single lead body, of electrodes, for stimulation and sensing, along with the physiological sensor poses some challenges for conductor routing in order to maintain a low profile for the lead body, without jeopardizing electrical isolation.